1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a liquid crystal display device and a fabricating method thereof.
2. Discussion of the Related Art
Until recently, display devices have typically used cathode-ray tubes (CRTs). In recent years, many efforts have been made in studying and developing various types of flat panel displays, such as liquid crystal display (LCD) devices, plasma display panels (PDPs), field emission displays (FED), and electro-luminescence displays (ELDs), as a substitute for CRTs. Of these types of flat panel displays, the LCD devices have several advantages, such as high resolution, light weight, thin profile, compact size, and low voltage power consumption.
In general, an LCD device includes two substrates that are spaced apart and face each other with a liquid crystal material interposed between the two substrates. The two substrates include electrodes that face each other such that a voltage applied between the electrodes induces an electric field across the liquid crystal material. Alignment of the liquid crystal molecules in the liquid crystal material changes in accordance with the intensity of the induced electric field into the direction of the induced electric field, thereby changing the light transmittance of the LCD device. Thus, the LCD device displays images by varying the intensity of the induced electric field.
FIG. 1 is a perspective view of an LCD device according to the related art. As shown in FIG. 1, the LCD device 11 includes a first substrate 22, a second substrate 5 and a liquid crystal material 14. The second substrate 5 is referred to as a color filter substrate that includes a color filter pattern 8, a black matrix 6 between the color filter patterns 8, and a common electrode 18 on both the color filter pattern 8 and the black matrix 6. The first substrate 22 is referred to as an array substrate that includes a data line 15 and a gate line 13 that cross each other to define a pixel region “P”. A pixel electrode 17 and a thin film transistor “T”, as a switching element, are positioned in each pixel region “P”. Thin film transistors “T”, which are disposed adjacent to the crossing of the data lines 15 and the gate lines 13, are disposed in a matrix form on the first substrate 22. A storage electrode 30 overlaps the gate line 13 to define a storage capacitor “C”.
The first and second substrates 22 and 5 have patterns that block light. The first and second substrates 22 and 5 are aligned to each other and then attached. There is a possibility of light leakage in the LCD device due to a misalignment between the first and second substrates 22 and 5. Accordingly, an LCD device where a color filter pattern is formed on the array substrate has been used. Such an LCD device is referred to as a color filter-on-transistor (COT) type LCD device.
FIG. 2 is a cross-sectional view of a COT type LCD device according to the related art. As shown in FIG. 2, the COT type LCD device “LC” includes first and second substrates 30 and 70 attached by a sealant 60. A gate line 32 and a data line (not shown) cross each other to define a pixel region “P” on the first substrate 30. A thin film transistor “T” includes a gate electrode 33, a semiconductor pattern 38, and source and drain electrodes 40 and 42. A gate pad electrode 34 and a gate pad electrode terminal 58 are disposed at one end of the gate line 32. Color filter patterns 52a and 52b are disposed on a passivation layer 50 in each pixel region “P”. A black matrix “BM” corresponds to the thin film transistor “T”. A pixel electrode 56 is disposed on the color filter patterns 52a and 52b. A light shielding pattern 72 is disposed at periphery portions of the second substrate 70. A common electrode 74 is disposed on the second substrate 70 to induce a vertical electric field with the pixel electrode 56.
In the related art COT type LCD device, since the color filter patterns and the thin film transistor are formed on the same substrate, a margin of error to compensate for misalignment during attachment of the first and second substrates is not required. However, since the related art COT type LCD device uses a twisted-nematic (TN) liquid crystal material operated by the vertically induced electric field, viewing angles are limited and thus display quality is degraded.